Inhomogeneous strain in individual quantum dots probed by transport measurements

Akyüz, C. D.; Zaslavsky, Alexander; Freund, L. B.; Syphers, D. A.; Sedgwick, T. O.

doi:10.1063/1.121169

Cited by 13 publications

(20 citation statements)

References 14 publications

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“…This has been observed in resonant tunneling diodes restricted to small pillars. 6 The calculation is readily extended to a slab of nonuniform composition, where ⑀ 0 (z) acquires an arbitrary variation during growth. The strains at the surface are again given by Eq.…”

Section: Figmentioning

confidence: 99%

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Relaxation of a strained quantum well at a cleaved surface

Davies¹,

Bruls²,

Vugs³

et al. 2002

Journal of Applied Physics

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Scanning probe microscopy of a cleaved semiconductor surface provides a direct measurement of the elastic field of buried, strained structures such as quantum wells or dots, but allowance must be made for relaxation at the surface. We have calculated this relaxation analytically for the exposed edge of a strained quantum well within classical elastic theory for a linear, isotropic, homogeneous medium. The surface bulges outward if the quantum well has a larger natural lattice constant and the dilation changes sign near the surface, which may enhance recombination. Results are given for a well of constant composition or an arbitrary variation along the growth direction and compared with cross-sectional scanning tunneling microscopy of InGaAs quantum wells in GaAs. Consistent values for the composition of the wells were obtained from counting In atoms, x-ray diffraction, and photoluminescence. The lattice constant on the surface and the normal relaxation were compared with the calculation. Qualitative agreement is good but the theory gives only about 80% of the observed displacement. Some of this difference can be explained by the larger size of indium atoms compared with gallium, and the different surface reconstruction and buckling behavior of InAs and GaAs ͑110͒ surfaces upon cleavage.

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Section: Figmentioning

confidence: 99%

“…Similar relaxation occurs at the edge of a wafer containing an otherwise uniform strained layer, or if the edge of the layer is exposed by etching a mesa or quantum pillar. 6 In Sec. II we present an analytic calculation of the relaxation at a cleaved surface through a mismatched quantum well, such as InGaAs in GaAs.…”

Section: Introductionmentioning

confidence: 99%

Relaxation of a strained quantum well at a cleaved surface

Davies¹,

Bruls²,

Vugs³

et al. 2002

Journal of Applied Physics

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“…Strain from lattice mismatch is needed to explain the properties of resonant tunneling diodes in Si/SiGe nanowire heterostructures. 24 It has been suggested that strains from lattice defects can be problematic in Si/SiGe QDs. 25 In contrast, we focus on the impact of the strain from metal gates, which are routinely used without consideration of the elastic strain caused by them.…”

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confidence: 99%

Formation of strain-induced quantum dots in gated semiconductor nanostructures

Thorbeck

Zimmerman

2015

AIP Advances

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Elastic strain changes the energies of the conduction band in a semiconductor, which will affect transport through a semiconductor nanostructure. We show that the typical strains in a semiconductor nanostructure from metal gates are large enough to create strain-induced quantum dots (QDs). We simulate a commonly used QD device architecture, metal gates on bulk silicon, and show the formation of strain-induced QDs. The strain-induced QD can be eliminated by replacing the metal gates with poly-silicon gates. Thus strain can be as important as electrostatics to QD device operation operation.

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“…As the lateral size of the structures decreases, an unambiguous reduction of the HH-LH energy separation corresponding to strain relaxation has been observed. 7,8 As the size of the dot is reduced further, additional fine structure is observed in the HH and LH resonant peaks, consistent with lateral quantization due to nonuniform strain. 8,9 The HH fine structure is generally stronger, because the states arising from the HH subband have a lighter in-plane mass 5 and hence are more strongly quantized by the lateral inhomogeneous strain-induced potential.…”

Section: Introductionmentioning

confidence: 68%

“…This has been demonstrated by Raman spectroscopy 6 and resonant tunneling measurements. [7][8][9] Since the HH-LH subband energy separation contains a large strain-induced contribution, 5 the HH and LH peak spacing is an experimentally accessible indication of the strain in the structure. As the lateral size of the structures decreases, an unambiguous reduction of the HH-LH energy separation corresponding to strain relaxation has been observed.…”

Section: Introductionmentioning

confidence: 99%

Quantum confinement induced by strain relaxation in an elliptical double-barrierSi∕SixGe1−xresonant tunneling quantum dot

et al. 2006

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Starting with a double-barrier p-Si/ Si 0.75 Ge 0.25 resonant tunneling heterostructure, we fabricated sub-100-nm elliptical quantum dots. Sidewall strain relaxation in the Si x Ge 1−x layer induces a lateral confining potential that quantizes heavy hole ͑HH͒ and light hole ͑LH͒ states in the SiGe quantum well, leading to fine structure in the HH-LH I͑V͒ resonant tunneling curves at low temperature. In this paper, we present the magnetotunneling I͑V , B͒ characteristics of heavy holes and light holes in magnetic fields B parallel to the tunneling current. From the evolution of the fine structure, we observe the competition between the straininduced lateral confinement potential and the magnetic confinement, from which we infer lateral potentials of HH and LH different from those of previously studied cylindrically symmetric dots. The experimental data are in qualitative agreement with inhomogeneous strain-induced HH and LH potential obtained via a full threedimensional finite-element strain simulation.

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Inhomogeneous strain in individual quantum dots probed by transport measurements

Cited by 13 publications

References 14 publications

Relaxation of a strained quantum well at a cleaved surface

Relaxation of a strained quantum well at a cleaved surface

Formation of strain-induced quantum dots in gated semiconductor nanostructures

Quantum confinement induced by strain relaxation in an elliptical double-barrierSi∕SixGe1−xresonant tunneling quantum dot

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